In order to obtain an optimum torque and an optimum output of an engine, an electric variable cam timing (VCT) system grasps an operation state such as a rotation speed and an accelerator opening degree, and continuously controls a phase of a cam. In this manner, the electric variable cam timing system optimizes opening and closing timing of an intake valve for supplying an air to the engine and an exhaust valve for discharging an exhaust gas. In Patent Literature 1, in the case where the engine is stopped when the cam is in an advance angle state, a phase angle of the cam is set to a most retarded angle at the time of a next starting to thereby improve the startability.